One man has managed to survive a world ravaged by hunger with his own small farm hidden within the woods. However when two women arrive at his door looking for shelter and food he suddenly finds his peaceful existence is threatened.
For me the Survivalist is a really smart low budget sci fi that has one central idea that sort of runs out of steam towards the end. I still enjoyed my time with the film, but some of the events towards the very end of the film feel to me as if the filmmakers knew they had run out of steam with the original idea so had to up the ante.
However, the central idea about a world in which nature has taken over because humans have lost touch with their farming/hunting/gathering roots is a good one, and it is well explored here. The performances are strong especially from Mia Goth whom you may have seen in the Nymphomaniac films.
Overall, if you are looking for something a little different from your sci fi then I recommend the Survivalist.